爲什麼這個java代碼不起作用有沒有錯誤

-2

package setup; 

import com.mysql.jdbc.Connection; 
import com.mysql.jdbc.Statement; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import javax.swing.JOptionPane; 
import javax.swing.table.DefaultTableModel; 

public class frnd_list extends javax.swing.JFrame { 
String x=null; 

public frnd_list(){ 
    initComponents(); 
    DefaultTableModel x=(DefaultTableModel)tbl.getModel(); 

    try { 
    int zx=0; 

Class.forName("java.sql.Driver"); 

Connection c=(Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/dtb","root",""); 
Statement s=(Statement) c.createStatement(); 
String q="select fullname, username from acc ;"; 

ResultSet rs=s.executeQuery(q); 


while (rs.next()) 
{ 
    String a1=rs.getString("fullname"); 
    String a2=rs.getString("username"); 
String a3=a1+" ("+a2+")"; 
zx=zx+1; 

x.addRow(new Object[]{a3});} 
System.out.print(zx); 


} 

catch(Exception e){JOptionPane.showMessageDialog(null,e.getMessage()); 

} 
    } 

    @SuppressWarnings("unchecked") 
    private void initComponents() { 

     jScrollPane1 = new javax.swing.JScrollPane(); 
     tbl = new javax.swing.JTable(); 
     jButton1 = new javax.swing.JButton(); 
     jButton2 = new javax.swing.JButton(); 

     setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 

     tbl.setModel(new javax.swing.table.DefaultTableModel(
      new Object [][] { 
       {null} 
      }, 
      new String [] { 
       "friend List" 
      } 
     ) { 
      boolean[] canEdit = new boolean [] { 
       false 
      }; 

      public boolean isCellEditable(int rowIndex, int columnIndex) { 
       return canEdit [columnIndex]; 
      } 
     }); 
     jScrollPane1.setViewportView(tbl); 

     jButton1.setText("Dashboard"); 
     jButton1.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       jButton1ActionPerformed(evt); 
      } 
     }); 

     jButton2.setText("Profile"); 
     jButton2.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       jButton2ActionPerformed(evt); 
      } 
     }); 

     javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); 
     getContentPane().setLayout(layout); 
     layout.setHorizontalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(layout.createSequentialGroup() 
       .addContainerGap() 
       .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 370, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addContainerGap()) 
      .addGroup(layout.createSequentialGroup() 
       .addGap(23, 23, 23) 
       .addComponent(jButton1) 
       .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
       .addComponent(jButton2) 
       .addGap(68, 68, 68)) 
     ); 
     layout.setVerticalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(layout.createSequentialGroup() 
       .addContainerGap() 
       .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 263, javax.swing.GroupLayout.PREFERRED_SIZE) 
       .addGap(7, 7, 7) 
       .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
        .addComponent(jButton1) 
        .addComponent(jButton2)) 
       .addGap(0, 14, Short.MAX_VALUE)) 
     ); 

     pack(); 
    }      

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {           

this.setVisible(false); 
dashboard obj = new dashboard(x); 
obj.setVisible(true); 
    }           

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {           
    this.setVisible(false); 
    new profile().setVisible(true); 
    }           

    public static void main(String args[]) { 
     try { 
      for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) { 
       if ("Nimbus".equals(info.getName())) { 
        javax.swing.UIManager.setLookAndFeel(info.getClassName()); 
        break; 
       } 
      } 
     } catch (ClassNotFoundException ex) { 
      java.util.logging.Logger.getLogger(frnd_list.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
     } catch (InstantiationException ex) { 
      java.util.logging.Logger.getLogger(frnd_list.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
     } catch (IllegalAccessException ex) { 
      java.util.logging.Logger.getLogger(frnd_list.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
     } catch (javax.swing.UnsupportedLookAndFeelException ex) { 
      java.util.logging.Logger.getLogger(frnd_list.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
     } 

     java.awt.EventQueue.invokeLater(new Runnable() { 

      public void run() { 
       new frnd_list().setVisible(true); 
      } 
     }); 
    } 
    private javax.swing.JButton jButton1; 
    private javax.swing.JButton jButton2; 
    private javax.swing.JScrollPane jScrollPane1; 
    private javax.swing.JTable tbl; 
}

這段代碼沒有一個錯誤。但每次我調試它，而不是打開GUI接口，它只顯示綠色焦點的下一行「公共frnd_list（）{」線獲得綠色焦點我不知道這是否意味着？爲什麼這個java代碼不起作用有沒有錯誤

來源

2012-05-28 AK SH AY

「這段代碼中沒有一個錯誤」 - 你是說你認爲它是完美的，還是它編譯的？這兩個索賠之間有很大的區別... –

另外，您使用哪個IDE來運行此程序？它必須是Netbeans或Eclipse，而不是兩者。此外，你有一些可怕的命名問題。 – adarshr

請將該代碼減少到顯示問題的最小量。目前有太多不相關的代碼需要通過。 – Confusion